1. Field
The following description relates to a method and apparatus for controlling distortions of an amplifier.
2. Description of the Related Art
An amplifier may be used to modulate and amplify input signals. In an output terminal of an amplifier, for example, a digital amplifier, generally, active elements such as transistors are formed in a bridge structure. Accordingly, in order to normally operate the amplifier, constant external power may need to be supplied to the output terminal.
However, if a supply voltage to be applied to the output terminal is cut off intermittently or fluctuates, the output signal of the amplifier may be distorted. In the case of a digital amplifier which processes audio signals, such supply voltage fluctuations may cause deterioration of the sound quality.
A number of solutions have been proposed. One method is to adopt a power supply with a sufficient capacity to provide the constant supply voltage to an output terminal of an amplifier. However, this method may not be practical due to the manufacturing cost of providing such a power supply.
Another method proposed is to compensate for supply voltage fluctuations by controlling changes in characteristics caused by the supply voltage fluctuations. An example is a feedback scheme to compensate the differences between output signals and ideal signals of the supply voltage. However, since such a feedback control scheme uses error signals generated in a previous operation, controlling the changes in real-time may be difficult. Furthermore, in such a method, a solution may not be available for supply voltage fluctuations occurring in transitional periods such as the start and end of a control operation.